The invention relates to a fuel feed unit for feeding fuel from a fuel tank, having a fuel pump drawing in fuel from a swirl pot, a suction jet pump feeding fuel from the fuel tank into the swirl pot, and a pump fluid line led to the suction jet pump from the delivery side of the fuel pump.
Such fuel feed units are commonly used in modern motor vehicles and are known in practice. The suction jet pumps are supplied with fuel by the fuel pump and feed fuel from the fuel tank into a swirl pot of the fuel feed unit, for example. In the known feed units fuel is delivered irrespective of whether fuel is present in the swirl pot.
The suction jet pump, particularly in demand-controlled feed units, in which the delivery capacity of the fuel pump is controlled as a function of the fuel demand of an internal combustion engine of the motor vehicle, is designed in such a way that it delivers sufficient fuel even in the event of a low delivery pressure of the fuel pump. This means, however, that in most operating states the suction jet pump receives an unnecessarily large amount of fuel as pump fluid, which requires the use of an especially high-performance pump unit.
DE 195 04 217 A1 discloses a fuel feed unit having a suction jet pump, in the pump fluid line of which a pressure valve is arranged, downstream of which is a separately arranged restrictor. The function of the pressure valve is to open the pump fluid line only once a specific is attained.
The object of the invention is to develop a fuel feed unit of the aforementioned type so that an unnecessary fuel feed to the suction jet pump is avoided, particularly in demand-controlled feed units.